Device for light irradiation onto tissue

ABSTRACT

A method and device for inducing or promoting growth and proliferation of skin cells or tissue or for controlling bacterial skin infection is described. The skin cells are irradiated with a low-intensity broad spectrum light at a wavelength of between about 340 to 3,000 nm. The increase in rate of cultivated cells is useful for example to obtain skin-like tissue needed for skin grafts or for promoting healing of skin wounds or lesions. Light-induced skin bacteria control is useful for example in the treatment of bacterial infections of the skin.

CROSS REFERENCE TO RELATED APPLICATION

The present application is the national stage under 35 U.S.C. 371 ofPCT/IL97/00375, filed Nov. 18, 1997.

FIELD OF THE INVENTION

The present invention concerns a method and device for affecting growthand proliferation of cells or tissue by light irradiation. The deviceand method of the invention are useful in increasing the rate of growthand proliferation of skin epithelial cells. Another use of the inventivedevice and method is the controlling bacterial infections of the skin,e.g. in the case of acne vulganison. The device and method of theinvention may thus be employed in the treatment of skin, oral or vaginaswounds or lesions, as well as irradiating keratinocytes in culture toincrease the yield of the culture.

In the following, irradiation of light intended to increase rate ofgrowth and proliferation of cells will be referred to herein at times as“light-induced growth acceleration”; treatment for the purpose ofcontrol of bacterial infections will be referred to herein at times as“light-induced bacteria control”; treatment of skin or oral wounds orlesions by light irradiation for the purpose of accelerating healing,will be referred to herein at times as “light therapy”.

LIST OF PRIOR ART

The following is a list of prior art considered to be relevant as abackground to the invention:

1. Mester, E.: Clinical results of laser stimulation and experimentalstudies on the mechanism of action Minerva Med., 72:2195-2199 (1981).

2. Lyons R. F., Abergel, R. P., White, R. A., Dwyer R. M., Castel, J.C., Uitto, J.: Biostimulation of wound healing in vivo by Helium-neonlaser, Ann. Plast. Surg., 18:47-50 (1987).

3. Surinchak, J. S., Alago, M. L., Bellamy R. F., Stuck, B. E., Belkin,M.: Effects of low-level energy lasers on the healing of full-thicknessskin defects, Lasers Surg. Med., 2:267-274 (1983).

4. Chavrier, C., Hartmann, S., Couble M. L., Msloire H.: Laser ainfra-rouge et cicatrisation conjunoctive en chirurgie parodontale, J.Parod., 5:209-212 (1986).

5. Lubart R., Wollman, Y, Friedman, H: Effects of visible and near IRlasers on cell cultures, J. Photochem. Photobiol. B. Biol., 12:305-311(1992).

6. Lubart, R., Friedman, H., Peled, I, Grossman, N: Light effect onfibroblast proliferation, Laser Therapy, 5:55-57 (1993).

7. Grossman, N., Reuveni, H., Halevy, S., Lubart, R: Visible lightpromotes proliferation of normal skin cells, J. Invest. Dermatol.,102:649A (1994).

8. Kjeldstad B., Photoinactivation of propionibacterium acnes by near UVlight, Z. Naturfersch 39(C):300-302 (1984).

9. Relø, T. B., Reisaeter G., and Johnson, A., Photodestruction ofpropionibacterium acnes porphysins, Z. Naturfersch, No. C 125-128(1985).

The above prior art documents will be referred to in the text byindicating their numbers from the above list within brackets. It shouldbe noted that the acknowledgement of these references herein does notamount to an indication that these are by any way relevant to the issueof patent-ability of the appended claims.

BACKGROUND OF THE INVENTION

Light therapy using low energy visible or near infrared light sourceshas been known to have a beneficial biological effect on a variety oftissues. Thus, during the last decade, low energy lasers (LEL) wereintroduced in treatment of wounds or lesions in a variety of tissue. LEL(mainly He—Ne lasers) has been proven effective in patients in promotingepithelization in full thickness skin defects, as well as forgynecological problems and lesions in oral epithelia^((1,2,3,4)).

In treatment of acute massive burn wounds, particularly such that coverlarge portions of the body area, it is necessary to bring to regrowth ofskin over the burnt area, the standard medical practice of grafting ofautologous tissue is very often complicated by the relative shortage ofautologous donor sites. A primary advance towards this problem has beenthe development of an in vitro cultivation technique for human epidermalkeratinocytes. The main disadvantage of such cultivation methods is thatit requires a period of three to six weeks to obtain sufficiently largequantities of cultured tissue ready for grafting.

Studies with skin derived cultured cells (normal human fibroblasts andkeratinocytes) showed that irradiation of visible, near infrared or nearultraviolet (UVA) light at low energy densities, was effective inpromoting proliferation of the cells; against this, irradiation athigher energy densities inhibited cell growth^((5,6,7)). Light in theUVA and in the visible light range was found to destroy bacteria such asPropionibacterium acnes^((8,9)). Radiation sources used hithertoincluded a variety of monochromatic and non-monochromatic light sources,irradiated at a wavelength of 360 nm (UVA), 540 nm and 600-900 nm, aswell as HeNe 632 nm lasers and 780 nm diode lasers. It should be notedthat similar light sources are used for selective destruction of tumorsby photoactivation of sensitizing drugs, in a technique known asphotodynamic therapy (PDT).

A common problem associated with all prior art used light sources isthat they are relatively complicated and expensive, and not readilyavailable to physicians.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a method and device forlight induced growth modulation of skin or epithelial cells.

It is an object in accordance—with one embodiment of the invention toprovide such a method and device for light-induced growth accelerationof skin or epithelial cells, such as fibroblasts and keratinocytes, inculture.

It is an object in accordance with another embodiment of the inventionto provide a method and device for light-induced bacteria control on theskin as an epithelium, e.g. and or vaginal epithelium.

It is an object in accordance with a further embodiment of the inventionto provide a method and device useful in light therapy of wounds orlesions.

The present invention provides, by a first of its aspects, a method ofinducing or promoting growth and proliferation of skin cells or tissueor for controlling bacterial skin infection, comprising irradiating theskin cells with a low-intensity broad spectrum light at a wavelengthbetween about 340 to 3,000 nm.

The present invention provides, by another of its aspects, a device foruse in promoting or inducing growth and proliferation of skin cells orfor controlling bacterial skin infection, the device comprising a lightsource which comprises a lamp emitting a broad spectrum light at awavelength between about 360 to 3,000 nm. The device may furthercomprise a focusing assembly as well as a light filtration assembly.

For some uses, e.g. irradiation onto wounds or lesions within the mouthor vaginas, the device may be equipped with a fiber optic so as todeliver the light to the desired site.

In accordance with one embodiment, the method and device are used forlight-induced growth acceleration cells, e.g. skin cells, in culture,i.e., to induce or promote growth and proliferation of these cells. Thedevice and method in accordance with this embodiment are particularlyuseful in increasing the rate of cultivation of such cells in order torapidly obtain skin-like tissue for grafting onto burn wounds. Thedevice in accordance with this embodiment may comprise a lens adapted todiffuse the light onto the entire surface of the culture, or means tomove the light skin, periodically across the culture.

In accordance with another embodiment, the method and device are usedfor light-induced skin bacteria control. Skin bacteria control includesdestruction of bacterial cells, as well as arresting growth andproliferation of the bacteria. It was found in accordance with theinvention that the destruction of bacteria by light irradiation isimproved in an oxygen rich environment; accordingly by a preferredembodiment of the invention the bacteria skin control is a combinedirradiation and oxygen flows into the skin. By another preferredembodiment the oxygen is supplied as a peroxide, e.g. H₂O₂.

In accordance with another embodiment of the invention, the method anddevice are utilized for light therapy of skin as epithelium for inducingor promoting healing of skin wounds or lesions.

DETAILED DESCRIPTION OF THE INVENTION

Unlike the prior art, the present invention utilizes a light source,which is not coherent and not polarized and is capable of irradiatingrelatively large tissue areas. In order to induce a positive, i.e. aregeneration stimulating effect on the skin or epithelium, the lightintensity should preferably be below about 800 mW/cm². It is clearhowever that for effective light therapy, the light intensity cannot betoo low since otherwise there will likely be no effect. Typically, alower limit of light intensity would be about 1 mW/cm². A preferredrange of light intensity is 10-200 mW/cm².

The light source used in accordance with this invention emits, a “white”light, i.e. a light source emitting light of a broad spectrum coveringthe entire visible and optionally also the near infrared spectrum. Anexample of such a light source is a halogen lamp which emits light atwavelengths within the range of 340 to 3,000 nm. In order to avoidheating of the target, the IR portions of the emitted light maytypically be filtered out so as to obtain light irradiation on thetarget at a wavelength within the range of about 340 to 1,200 nm,preferably within the range of about 340 to 800 nm.

In addition, the light may also be filtered through a UV filter forfiltering out this harmful portion of the spectrum, thereby increasingsafety.

The device in accordance with the invention may typically also comprisea lens for focusing the light onto the target cells or tissue.

Light may be irradiated either continuously or in pulses. Continuouslight irradiation will typically be preferred in lower light intensitieswhile pulsed irradiation will be preferred in higher light intensities.The decision whether to use constant irradiation of pulsed lightirradiation depends on the exact application and on the total desiredirradiation.

It will no doubt be clear to the artisan that the effect of the lightdepends both on the light intensity as well as on the duration ofirradiation. In other words, high intensity irradiation requires a lowerduration than a low intensity irradiation. Clearly, when depending onthe duration of a pulsed light the net light time should be factored.

The effect of irradiation may at times be enhanced by the addition ofphotosensitizer substances to the target cells or tissue. For example, aculture of fibroblasts or keratinocytes may be supplemented with smallamounts of a photosensitizer substance, such as hematoporphyrinderivatives prior to light irradiation. Such substances may also beapplied topically onto the skin prior to the light therapy. Theconcentration of such substance is typically substantially lower thanconcentrations used in photodynamic therapy.

The invention will be illustrated further by the following examples:

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation showing the percent of dividingfibroblast cells following their irradiation with a light sourceconsisting of a 40 mW/cm² halogen lamp.

FIG. 2 is a schematic representation showing the optical density (OD) at660 nm of propionibacterium acne cultures at various periods of timefollowing their irradiation with a light source at 550 mW/cm² for 90mins. The OD of the irradiated cultures was compared to a similarculture which was not subjected to irradiation.

EXAMPLE 1

3T3 NIH fibroblast cells were seeded in 25 or 96 multi-well plates. Theconcentration of cells was about 2.5×10³-10⁴ cells/well, respectively.48 hours later cells were washed and exposed to light from a lightsource consisting of a 40 mW/cm² halogen lamp for various periods oftime (in triplicate) while in the phosphate buffered saline (PBS).Following irradiation, the cultures were replenished with fresh growthmedia and were further incubated for 24-72 hours. At the end of theincubation, the cultures were washed with PBS and trypsinized.

FIG. 1 shows the percent of proliferating cells that were divided 24hours after irradiation. As can be seen, the number of dividing cellspeaked in the culture which had been previously irradiated with thelight source for 1 min.

This experiment demonstrates that irradiation of keratinocytes withlight emitted from a halogen lamp accelerates growth and proliferationof these cells. This may be useful in growing tissue for skin grafts,wherein appropriate irradiation of the cells may result in a decrease inthe time required to obtain a specific amount of such in vitro growthtissue.

EXAMPLE 2

17 young individuals who had adolescent wounds were treated byirradiation of their facial skin, using a device in accordance with theinvention. The treatment of each individual consisted of threeirradiations per week, each one with a light intensity of 40 mW/cm² fortwo minutes on the infected area.

The tested individuals reported dramatic improvement in their facialconditions and examination of the individuals showed that after thistreatment, their faces had no wounds and no scars.

This clearly demonstrates the beneficial effect of irradiation with ahalogen lamp on the treatment of skin wounds or lesions.

EXAMPLE 3

Individuals with adolescent wounds were treated by irradiating theirfacial skin similarly as in Example 2. A 2-3% H₂O₂ solution was appliedonto the skin shortly before the irradiation.

A marked improvement in the individual's condition was observed.

EXAMPLE 4

50 individuals who had Herpes on their lip were treated twice or threetimes a day with the light source as described above. Each treatment wasat 120 mW/cm² for 2 mins. Two to three days after beginning of thetreatment, a significant improvement (decrease in severity of infection)was observed.

EXAMPLE 5

Cultures of propionibacterium acnes were irradiated with the lightsource described above at 550 mW/cm² for 90 mins. As seen in FIG. 2,irradiation of the cells resulted in inhibition of their growth ascompared to no-irradiated control cells.

What is claimed is:
 1. A method of inducing or promoting growth andproliferation of cells or tissue, comprising irradiating the cells ortissue with a low-intensity broad spectrum light at wavelengths betweenabout 340 to 3,000 nm with a light intensity and for a time selected toinduce or promote proliferation of the cells or tissue, provided that ifthe lower limit of the wavelength spectrum is 600 nm, the upper limit isother than 900 nm.
 2. A method according to claim 1, wherein the lightirradiation is at a light intensity of below about 800 mW/cm².
 3. Amethod according to claim 2, wherein the light intensity is at a rangeof about 10 to 200 mW/cm².
 4. A method according to claim 1, wherein thecells are cultured skin cells.
 5. A method according to claim 1, fortreatment of skin in order to induce or promote healing of skin woundsand lesions wherein the skin is constituted by the cells or tissue.
 6. Amethod according to claim 5, further comprising applying oxygen or aperoxide solution onto the skin.
 7. The method of claim 1 wherein thebroad spectrum light is white light.
 8. The method of claim 1 furthercomprising applying to the cells or tissue a photosensitive substanceselected to enhance the effect of the light.
 9. A method for controllingbacterial infections of skin or epithelium comprising irradiating theskin or epithelium with a low-intensity broad spectrum light atwavelengths between about 340 to 3,000 nm with a light intensity and fora time selected to control bacterial infections of the skin orepithelium.
 10. A method according to claim 2, wherein the wavelength ofthe light is between about 340 to 1,200 nm.
 11. The method of claim 9wherein the broad spectrum light is white light.
 12. The method of claim9 further comprising applying to the skin or epithelium a photosensitivesubstance selected to enhance the effect of the light.
 13. A method ofinducing or promoting growth and proliferation of cells or tissuecomprising: (a) selecting cells or tissue in which growth andproliferation are to be induced or promoted; and (b) irradiating theselected cells or tissue with a low-intensity broad spectrum light atwavelengths between about 340 to 3,000 nm, provided that the irradiationis not with a broad spectrum light at 600-900 nm, thus inducing orpromoting growth and proliferation of the selected cells or tissue. 14.The method of claim 13 wherein the broad spectrum light is white light.15. A method of inducing or promoting growth and proliferation of cellsor tissue, comprising irradiating the cells or tissue with at least onelow-intensity broad spectrum light covering an entire spectrum between alower wavelength of 340 nm or more and an upper wavelength of 3,000 nmor less with a light intensity and for a time selected to induce orpromote proliferation of cells or tissue, provided that if the lowerlimit of the wavelength spectrum is 600 nm, the upper limit is otherthan 900 nm.
 16. The method of claim 15 wherein the broad spectrum lightis white light.
 17. A method of inducing or promoting growth andproliferation of cells or tissue comprising: (a) selecting cells ortissue in which growth and proliferation are to be induced or promoted;and (b) irradiating the selected cells or tissue with at least onelow-intensity broad spectrum light covering an entire spectrum between alower wavelength of 340 nm or more and an upper wavelength of 3,000 nmor less, provided that the irradiation is not with a broad spectrumlight at 600-900 nm, thus inducing or promoting growth and proliferationof the selected cells or tissue.
 18. The method of claim 17 wherein thebroad spectrum light is white light.
 19. A method of controllingbacterial infections of skin or epithelium comprising: (a) selectingskin or epithelium in which bacterial infections are to be controlled;and (b) irradiating the selected skin or epithelium with a low-intensitybroad spectrum light at wavelengths between about 340 to 3,000 nm, thuscontrolling bacterial infections of the selected skin or epithelium. 20.The method of claim 19 wherein the broad spectrum light is white light.21. A method of controlling bacterial infections of skin or epithelium,comprising irradiating the skin or epithelium with at least onelow-intensity broad spectrum light covering an entire spectrum between alower wavelength of 340 nm or more and an upper wavelength of 3,000 nmor less with a light intensity and for a time selected to controlbacterial infections of the skin or epithelium.
 22. The method of claim21 wherein the broad spectrum light is white light.
 23. A method ofcontrolling bacterial infections of skin or epithelium comprising: (a)selecting skin or epithelium in which growth and proliferation are to beinduced or promoted; and (b) irradiating the selected skin or epitheliumwith at least one low-intensity broad spectrum light covering an entirespectrum between a lower wavelength of 340 nm or more and an upperwavelength of 3,000 nm or less, thus inducing or promoting growth andproliferation of the selected skin or epithelium.
 24. The method ofclaim 23 wherein the broad spectrum light is white light.